Alloy for the preparation of titanium-boron steel



Patented Nov. 4, 1952 ALLOY FOR THE PREPARATION OF TITANIUM-BORON STEELViatcheslav V. Efimofic, Niagara Falls, N. Y., as-

signor to National Lead Company, New York, N. Y., a corporation of NewJersey N Drawing. Continuation of application Serial No. 95,573, May 26,1949.

This application December 19, 1950, Serial No. 201,700

3 Claims.

This invention relates to alloys containing titanium, boron, andaluminum which are particularly adapted for use in the manufacture oftitanium-boron steels.

It has been previously known that steels containing about 0.3 to 0.5%titanium and 0.01 to 0.03% boron are characterized by superiorresistance to load at moderately high temperatures. Such steels may bemanufactured by adding to molten steel, after de-oxidizing, suitableamounts of metallic titanium and metallic boron, which preferably, areadded in the form of ferro-all-oys. At the temperatures at which thesealloys are added to the steel, loss by oxidation of the added elements,particularly the titanium, is, to some degree, inevitable. It ishelpful, therefore, to also add a de oxidizing agent such as aluminumwhich improves the recovery of the added titanium and boron byprotecting them from loss by oxidation, aluminum being more readilyoxidized than either of these metals. The presence of aluminum has alsobeen found to decrease the fusion poin'tan-d improve the solubility (inmolten steel) 01 ferro-titanium alloys. However, even under suchconditions, the recoveries of titanium and boron have been diificult topredict with sufficlent accuracy to insure the proper proportions ofthese added alloy elements in the final finished steel.

' It is, therefore, the object of the present invention to provide asingle alloy to be added to steel which will provide titanium and boronin proper proportions and which will insure high, uniform, predictablerecoveries of these metals in finished steel. It is another object ofthis invention to provide a, more efficient and economical method for.production of titanium boron alloy steel. These and other objects of theinvention will be apparent from the following description thereof.

This invention in its broadest aspects contemplates provision of analloy consisting of from about to of titanium, from about 1.5% to 2.8%boron, from about 8% to 15% aluminum and the remainder substantially alliron and incidental impurities. The impurities may include not more thanan insignificant percentage of carbon, about 0.1%, for reasonshereinafter explained in more detail. Such an alloy when added to moltensteel, after lie-oxidation, will produce titanium-boron steel in whichthe titanium recovery will be about and the boron recovery about Forillustration of a suitable method for preparation of an alloy accordingto this invention. the following example is shown:

2 Example 1 A mixture of the following:

46.5 lbs. calcined granular ilmenite 22 lbs. refined granular rutile 36lbs. pure grained aluminum 6 lbs. fused boric acid 10 lbs. sodiumchlorate with the following starting mix on top:

2 lbs. calcined granular ilmenite 1 lb. pure grained aluminum 0.5 lb.sodium chlorate was ignited to produce a titanium-boron-alumi nu=m ferroalloy by thermit reaction.

As a result of this reaction, 30 pounds of alloy containing 38.04%titanium, 14.39% aluminum, 2.61% boron, 1.08% silicon, 0.07% carbon andthe remainder substantially all iron, was obtained and separated fromthe slag.

An alternative method for preparation of the alloy of this inventionemploys ferrosilicon, pref-. erably high grade ferrosilicon e. g. 94%Si, in the ignited mixture which improves the efiiciency of the ther-mitreaction and therefore promotes better recovery of the alloyingredients. Under these conditions, alloys containing aluminum in thelower ranges, that is 7 to 10%, may be produced. The amount offerrosilicon in the origi-, nal mixture should be such that not morethan 4% silicon will be present in the product alloy, and in suchamounts this element will not significantly affect the action or theusefulness of the alloy since the amount of silicon introduced intotreated steel will have a negligible effect on the properties thereof.

An illustration of the manufacture of the alloy of this inventionemploying ferrosilicon in the starting mix is shown below.

Example 2 A mixture of the following:

66 lbs. calcined granular ilmenite (61 T102) 8 lbs. refined granularrutile 34 lbs. pure grained aluminum 6 lbs. fused boric acid 5 lbs.sodium chlorate lb. ferro silicon (94% Si) with the following startingmix on top:

1 lbs. calcined granular ilmenite (fil TiOz) 1b. pure grained aluminum 1lb. sodium chlorate was ignited to produce a titanium-boron-aluminumferro alloy by thermit reaction.

As .a result of this reaction, 33 lbs. of an alloy containing 41.76%titanium, 8.13% aluminum, 2.36% boron and the remainder substantiallyall iron with about 4% impurities, was obtained and separated from theslag. The impurities included 2.86% silicon derived from theferrosilicon employed in the original mixture.

A 100 lb. batch of molten, de-oxidized steel was treated by addition of1 lb. of the alloy made according to .Example 1. The alloy was added inthe form of lumps which dissolved readily in the steel forming atitanium boron steel containing 0.32% titanium and 0.023% boron.

The alloy of this invention comprises titanium, boron, and, aluminumwith the remainder iron except for the presence of incidental impuritieswhich may be derived from the ores and ingredients employed. Theseimpurities may include silicon, chromium, manganese, sulphur, phosphorusand other elements which in the amounts present, have negligible effecton the useful properties of the alloy. The alloy of this invention issubstantially carbon free and this element cannot be tolerated as animpurity in more than insignificant amounts for instance about 0.1%.This is necessary because the boron content of the finished steel willresult in hot shortness unless the carbon in the steel is completelystabilized by titanium. Hot-short steel cannot be rolled under the usualsteel mill conditions. Therefore, in order to preserve proper workingcharacteristics in the steel, it is essential to keep the carbon contentas low as possible and to insure that any amount present be stabilizedby titanium. The ranges of titanium, aluminum, and boron in the alloy ofthis invention are critical for the introduction of the desiredpercentages of titanium and boron in the steel with uniform and highefiiciency, and the titanium content of the alloy cannot also compensatefor the introduction of additional carbon, and under these conditions,the presence of any appreciable amount of carbon in the alloy of thepresent invention would seriously detract from its usefulness in themanufacture of titanium-boron steel. Such incidental impurities will notgenerally be present in excess of about 2% except when ferrosilicon isemployed in the manufacture of the alloy and under these conditions, dueto the presence of silicon, will not exceed about 6%.

The alloy of the present invention permits simultaneous addition oftitanium and boron to molten steel conveniently and economically by asingle addition which insures ready control of the proper percentages ofthese metals in the finished steel. The alloy of the present inventionconextent. The proportion of titanium present in the alloy according tothis invention is such that efficient and ready solution is obtained.Alloys containing more than about 45% titanium are difiicult to dissolvein steel, while if less than about 35 titanium is present, too large anaddition to steel is required to obtain the proper titanium content.Therefore, the range of titanium in the alloy of the present inventionis "be-- tween about 35% and 45% titanium; the boron content is adjustedso that the proper ratio of this element to the titanium is presentallowing for losses in the constituents of the alloy when employed inthe treatment of steel.

Employment of the single alloy of this invention has several advantagesover the addition of titanium and boron as separate ferro alloys. Thepresence of aluminum as a constituent of the alloy assures closeproximity of this metal, and therefore, more efficient protectionagainst oxidation losses in the added elements. Furthermore, theinevitable loss of titanium which is more or less readily oxidized atthe temperatures involved, is reasonably constant and the amountactually recovered can be predicted to insure the desired content in thefinished steel.

This application is a continuation of application, Serial No. 95,573filed May 26, 1949, now abandoned.

While this invention has been described and i1- lustrated by theexamples shown, it is not to be considered to be strictly limitedthereto and modifications and variations may be employed within thelimits of the following claims.

I claim:

1. An alloy of the class described consisting of from about 35% to 45%titanium, from about 1.5% to 2.8% boron, from about 7% to 15% aluminum,less than 0.1% carbon and the remainder iron and incidental impurities.

2. An alloy of the class described consisting of about 38% titanium,about 2.6% boron, about 14.4% aluminum, less than 0.1% carbon and theremainder iron and incidenta1 impurities.

3. A method for production of titanium boron alloy steel which comprisesadding to deoxidized steel while molten, an alloy consisting of fromabout 35% to 45% titanium, from about 1.5% to 2.8% boron, from about 7%to 15% aluminum, less than 0.1% carbon and the remainder iron andincidental impurities.

VIATCHESLAV V. EFIMOFF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,295,708 Comstock Sept. 15, 1942FOREIGN PATENTS Number Country Date 561,407 Great Britain May 18, 1944

1. AN ALLOY OF THE CLASS DESCRIBED CONSISTING OF FROM ABOUT 35% TO 45%TITANIUM, FROM ABOUT 1.5% TO 2.8% TO BORON, FROM ABOUT 7% TO 15%ALUMINUM, LESS THAN 0.1% CARBON AND THE REMAINDER IRON AND INCIENTALIMPURITIES.